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|
package dbus
import (
"fmt"
"strings"
"unicode"
"unicode/utf8"
)
// Heavily inspired by the lexer from text/template.
type varToken struct {
typ varTokenType
val string
}
type varTokenType byte
const (
tokEOF varTokenType = iota
tokError
tokNumber
tokString
tokBool
tokArrayStart
tokArrayEnd
tokDictStart
tokDictEnd
tokVariantStart
tokVariantEnd
tokComma
tokColon
tokType
tokByteString
)
type varLexer struct {
input string
start int
pos int
width int
tokens []varToken
}
type lexState func(*varLexer) lexState
func varLex(s string) []varToken {
l := &varLexer{input: s}
l.run()
return l.tokens
}
func (l *varLexer) accept(valid string) bool {
if strings.IndexRune(valid, l.next()) >= 0 {
return true
}
l.backup()
return false
}
func (l *varLexer) backup() {
l.pos -= l.width
}
func (l *varLexer) emit(t varTokenType) {
l.tokens = append(l.tokens, varToken{t, l.input[l.start:l.pos]})
l.start = l.pos
}
func (l *varLexer) errorf(format string, v ...interface{}) lexState {
l.tokens = append(l.tokens, varToken{
tokError,
fmt.Sprintf(format, v...),
})
return nil
}
func (l *varLexer) ignore() {
l.start = l.pos
}
func (l *varLexer) next() rune {
var r rune
if l.pos >= len(l.input) {
l.width = 0
return -1
}
r, l.width = utf8.DecodeRuneInString(l.input[l.pos:])
l.pos += l.width
return r
}
func (l *varLexer) run() {
for state := varLexNormal; state != nil; {
state = state(l)
}
}
func (l *varLexer) peek() rune {
r := l.next()
l.backup()
return r
}
func varLexNormal(l *varLexer) lexState {
for {
r := l.next()
switch {
case r == -1:
l.emit(tokEOF)
return nil
case r == '[':
l.emit(tokArrayStart)
case r == ']':
l.emit(tokArrayEnd)
case r == '{':
l.emit(tokDictStart)
case r == '}':
l.emit(tokDictEnd)
case r == '<':
l.emit(tokVariantStart)
case r == '>':
l.emit(tokVariantEnd)
case r == ':':
l.emit(tokColon)
case r == ',':
l.emit(tokComma)
case r == '\'' || r == '"':
l.backup()
return varLexString
case r == '@':
l.backup()
return varLexType
case unicode.IsSpace(r):
l.ignore()
case unicode.IsNumber(r) || r == '+' || r == '-':
l.backup()
return varLexNumber
case r == 'b':
pos := l.start
if n := l.peek(); n == '"' || n == '\'' {
return varLexByteString
}
// not a byte string; try to parse it as a type or bool below
l.pos = pos + 1
l.width = 1
fallthrough
default:
// either a bool or a type. Try bools first.
l.backup()
if l.pos+4 <= len(l.input) {
if l.input[l.pos:l.pos+4] == "true" {
l.pos += 4
l.emit(tokBool)
continue
}
}
if l.pos+5 <= len(l.input) {
if l.input[l.pos:l.pos+5] == "false" {
l.pos += 5
l.emit(tokBool)
continue
}
}
// must be a type.
return varLexType
}
}
}
var varTypeMap = map[string]string{
"boolean": "b",
"byte": "y",
"int16": "n",
"uint16": "q",
"int32": "i",
"uint32": "u",
"int64": "x",
"uint64": "t",
"double": "f",
"string": "s",
"objectpath": "o",
"signature": "g",
}
func varLexByteString(l *varLexer) lexState {
q := l.next()
Loop:
for {
switch l.next() {
case '\\':
if r := l.next(); r != -1 {
break
}
fallthrough
case -1:
return l.errorf("unterminated bytestring")
case q:
break Loop
}
}
l.emit(tokByteString)
return varLexNormal
}
func varLexNumber(l *varLexer) lexState {
l.accept("+-")
digits := "0123456789"
if l.accept("0") {
if l.accept("x") {
digits = "0123456789abcdefABCDEF"
} else {
digits = "01234567"
}
}
for strings.IndexRune(digits, l.next()) >= 0 {
}
l.backup()
if l.accept(".") {
for strings.IndexRune(digits, l.next()) >= 0 {
}
l.backup()
}
if l.accept("eE") {
l.accept("+-")
for strings.IndexRune("0123456789", l.next()) >= 0 {
}
l.backup()
}
if r := l.peek(); unicode.IsLetter(r) {
l.next()
return l.errorf("bad number syntax: %q", l.input[l.start:l.pos])
}
l.emit(tokNumber)
return varLexNormal
}
func varLexString(l *varLexer) lexState {
q := l.next()
Loop:
for {
switch l.next() {
case '\\':
if r := l.next(); r != -1 {
break
}
fallthrough
case -1:
return l.errorf("unterminated string")
case q:
break Loop
}
}
l.emit(tokString)
return varLexNormal
}
func varLexType(l *varLexer) lexState {
at := l.accept("@")
for {
r := l.next()
if r == -1 {
break
}
if unicode.IsSpace(r) {
l.backup()
break
}
}
if at {
if _, err := ParseSignature(l.input[l.start+1 : l.pos]); err != nil {
return l.errorf("%s", err)
}
} else {
if _, ok := varTypeMap[l.input[l.start:l.pos]]; ok {
l.emit(tokType)
return varLexNormal
}
return l.errorf("unrecognized type %q", l.input[l.start:l.pos])
}
l.emit(tokType)
return varLexNormal
}
|
